I had the same concern when I bought it, so I put the planet audio one on the bench and put a sine wave in from a calibrated sig generator, tested THD by comparing the input to the output with a dual channel scope. It is good 2 go. It's cheap because it's a closeout, they quit making them. Not many people need that many channels. List price was 250$ or so originally.

Psyclone, can you calculate THD without looking at the harmonic content from the output of the DUT and comparing it to the fundamental frequency used to excite the device? Or do you have a fancy scope that will measure it for you?

Thanks for the advice. I bought the Audio Contol Overdrive before I got Psyclones' advice.

I decided to get one because apparently my XMD1 doesn't hardly put out any voltage when my IPod is plugged through the CD changer input. I have the gain turned up all the way on all 3 of my amps and I can turn up the volume all the way on the XMD1 and the Ipod. I doesn't distort at all (which is wierd.) I hoping the line driver will give me more volume.

You can also do it with LabView or Matlab, that's (a little) cheaper and more useful than a big ass scope!!

I was originally going to get an Audiocontrol Matrix, but three different vendors cancelled the order, I think they were having manufacturing problems or something. For 1/4 the cost, I figured I'd try the planet audio. Works great so far.